1. Field of the Invention
The present invention relates to a novel substituted 1,2,4-triazine-3,5-dione derivative or a salt thereof and an anti-coccidial drug composition containing the same as an active component.
2. Description of the Related Art
Coccidiosis is an infectious disease caused by protozoans belonging to coccidium. Poultry is mainly infected with Eimeria tenella, Eimeria aceruvulina and Eimeria necatrix, and suffers from various troubles such as bleeding of the gastrointerstinal tract, mortality, growth inhibition, and so forth. Poultry includes chickens, turkeys, quails and ducks. Mass outbreak of avian coccidiosis in a commercial poultry farm imparts an extremely great loss to an owner and has often become a serious problem. Accordingly, the development of an anticoccidial drug composition which is effective for prevention and remedy of coccidiosis has drawn a keen attention of those concerned in the art.
Conventionally, sulfanilamides, nitrofurans, quinolines, antithiamines and benzoamides have been put into practical application as the anticoccidial drug, and polyether-based antibiotics have been used mainly at present. However, these compounds have the drawbacks in that, although their efficacy against coccidiosis is not very high, they are toxic to hosts. Moreover, resistant strains appear in the course of continuous use of these chemicals, and their efficacy drops progressively with time. In view of these circumstances, the development of a novel anticoccidial agent which is effective for the resistant strains and at the same time, hardly imparts resistance to the strains, has been desired earnestly.
Japanese Unexamined Patent Publication (Kokai) No. 47-9998 and No. 50-19763, German Unexamined Patent Publication No. 2532363 and Belgian Unexamined Patent Publication No. 851655 disclose a compound having a basic skeletal structure expressed by the following general formula (II) as a 1,2,4-triazine-3,5-dione derivative having an anticoccidial action: ##STR2## wherein A represents O, S, SO or SO.sub.2. However, these compounds have not been entirely satisfactory in the aspects of the anti-coccidium action, toxicity and the appearance of resistant strains.